At present, in the process of longwall mining, a 121 mining method as shown in FIG. 1, that is, firstly, two entries are excavated in the working face and one coal pillar is reserved for supporting. Specifically, each working face 10 includes an upper gateroad 11, a lower gateroad 12 and a mining face 13. The upper gateroad 11 of the individual working face 10 is connected to a haulage dip 14, and the lower gateroad 12 of the individual working face 10 is connected to an air-return dip 15, in addition, a track dip 16 is also provided. In such structure, the coal pillar needs to be reserved, which causes significant waste of resources. Moreover, it is required to excavate two entries for each working face, and thereby the work efficiency is low.
With development of a large-scale coal mining, amount of coal resources will be reduced day by day, especially in current downturn of the coal industry, the problems, such as high mining cost and low recovery rate of the coal, caused by reserving the coal pillar and excavating entries along the gob area, increasingly arise.
The Background portion contains the contents which are merely used for reinforcing understanding of the background technology of the present disclosure, and thus may include information that does not constitute the prior art as already known by an ordinary person skilled in the art.